Inventories



	March 31, 2018			December 31, 2017
Raw materials	$	38,093		$	48,502
Work in progress	57,025			50,511
Finished goods	34,425			35,430
Spares and other	23,563			23,091
	153,106			157,534
Reduction to LIFO cost basis	(28,471		)	(28,326		)
Total inventories – net	$	124,635		$	129,208

The decrease in Total inventories – net as of March 31, 2018 compared to December 31, 2017 is due primarily to lower levels of raw materials driven by the timing of cumene deliveries at March 31, 2018 and December 31, 2017.